as from experience today at Chaengwattana - Laos get 7 days extension only - on their 30days - even if they have medical issues - 7 days. If they want to stay longer, they have to obtain a visa.
if you leaving between you get on your 70days. - otherwise you need a RE-entry stamp, cause your normal Tr visa is single entry - setv , there is a metv as well, more complicated to do.